Galvanized steel and stainless steel band materials, which are normally used for clamp structures, are devoid of any significant elastic stretchability in the longitudinal direction of the band material. Nonetheless, these band materials have been and continue to be used almost exclusively with clamp structures that are commercially sold in very large quantities. The use of plastically deformable so-called "Oetiker" ears in conjunction with such band materials played an important role for the success of such clamp structures because the plastically deformable "Oetiker" ears are inherently capable of compensating for temperature and/or pressure changes, i.e., for increases or decreases in the required circumferential length of the clamp structure.
These "Oetiker" ears have been used by the millions in clamp structures made from tubular stock (endless-type clamps) as well as in clamp structures made from band material whose overlapping band portions are mechanically interconnected (open-type clamps). My prior U.S. Pat. No. 2,614,304 relating to a two-ear clamp with two "Oetiker" ears made from tubular stock, my prior U.S. Pat. No. 3,082,498 relating to one-ear clamps made from tubular stock or band material, my prior U.S. Pat. No. 2,847,742 relating to clamp structures made from ladder-type band material closed by the use of connecting members, my prior U.S. Pat. No. 3,286,314 relating to open-type clamp structures with rivet-like connections for the overlapping band portions, as well as the so-called stepless type clamp structures disclosed in my prior U.S. Pat. Nos. 4,299,012 and 4,315,348 also made from band material of the aforementioned type are representative of clamp structures which have been sold by applicant in very large quantities, whereby so-called "Oetiker" ears for tightening the clamp structure about an object to be fastened thereby are used in all of these clamp structures and whereby these "Oetiker" ears, when plastically deformed into more or less omega shape, automatically compensate for temperature and/or pressure changes.
As tolerances in the external hose dimensions, i.e., in the hose diameters are for all practical purposes unavoidable, these tolerances could be compensated by the degree of closing of the "Oetiker" ears because the clamping bands as such offered no significant stretchability in its longitudinal direction. This meant in practice that, for example, the gap underneath an ear plastically deformed with the same force, i.e., the spacing between the transitions from the clamping band into the plastically deformed omega-shaped ear could vary depending on external hose dimensions. This, in turn, led to the use of pneumatic pincer-like tools operating with predetermined pressure to assure a constant closing force in the plastic deformation of the "Oetiker" ears in order to assure substantially the same holding ability of the installed clamp structures. Such pneumatic pincer-like tools, used in large quantities, for example, on the assembly line of the automotive industry are relatively costly and require relatively expensive pneumatic systems with pressure-reducing valves. The problem of gap size under the ear can be minimized by insert members which can be made from relatively thin band material in order to minimize the step in the inner circumferential surface of the clamp, as disclosed in my prior U.S. Pat. No. 3,789,463. However, the use of such insert members increases the cost of the clamp structure. The so-called stepless clamp structures of the type disclosed, for example, in my U.S. Pat. No. 4,237,584, and more specifically in my two aforementioned U.S. Pat. Nos. 4,299,012 and 4,315,348 effectively eliminate the problem of the remaining gap under the plastically deformed ear. However, the use of the pneumatic pincer-like tools operating at constant pressure is still necessary if a constant closing pressure is desired. Moreover, as these pneumatic pincer-like tools operate with a constant pressure, they continue to entail the disadvantage that the ear cannot always be closed to maximize its holding ability. This is so as the degree of closing the ears under those conditions depends on the existing external dimensions of the hose, which may vary as explained above. However, maximum holding conditions with so-called "Oetiker" ears are attainable when the ear is plastically deformed in such a manner that the transitions from the clamping band into the plastically deformed ear are as close as possible in the circumferential direction and when the height of the plastically deformed ear is kept relatively low. Furthermore, as disclosed in the aforementioned parent application, so-called earless clamp structures where space conditions do not permit projecting parts, such as plastically deformed ears, are manufactured for a given diameter of the object to be fastened thereby. In the absence of a plastically deformable "Oetiker" ear and in the absence of any elastic stretchability in the clamping band itself, such earless clamp structures may pose problems when the external dimensions of the object to be fastened thereby, for example, the dimensions of the hose diameter experience excessively large tolerances.